Fuel injector-igniter



1962 c. H. MAY 3,060,913

FUEL INJECTOR-IGNITER Filed Feb. 15, 1960 2 Sheets-Sheet 1 /j INVENTOR. (742x12 b. //4y lilif'pm Oct. 30, 1 962 c. H. MAY

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trite fires int 3,060,913 FUEL INJECTOR-IGNITER Claude H. May, Racine, Wis., assignor to Walker Manufacturing Company, Racine, Win, a corporation of Delaware Filed Feb. 15, 1960, Ser. No. 8,797 Claims. (Cl. 123-33) This invention relates generally to internal combustion engines, and more particularly to a novel fuel injectorigniter for an internal combustion engine.

As explained in greater detail in application Serial No. 8,784, filed February 15, 1960, for Fuel Injector-Igniter a pronounced improvement in internal combustion systems may be obtained by effecting ignition of the fuel used to supply energy to the system immediately prior to introduction of the fuel into an expansion chamber. The present invention provides a structure for doing this which is somewhat different from that disclosed in my copending application.

Accordingly, the broad object of the present invention is an improved combustion system for an internal combustion engine.

Another object is a fuel injector-igniter that concurrently ejects and ignites a fuel.

Another object is a fuel injector-igniter wherein the ignition occurs at the onset of fuel injection and is of a continuous nature precluding ignition lag or delay prior to the initiation of combustion.

Another object is a fuel injector-igniter that is usable in conventional reciprocating piston engines.

A still further object of the invention is a fuel injectorigniter having a self-contained fuel metering means.

Another object is a fuel injector-igniter usable in place of the spark plug of a conventional gasoline engine.

Another object is a fuel injector-igniter that insures positive ignition of a fuel charge irrespective of ambient temperature.

Another object of the invention is the provision of a metering means integral with the fuel injector-igniter controlled solely by fuel pressure.

Other objects and advantages of the present invention will become apparent from the following detailed description wherein reference is made to the drawings in which:

FIGURE 1 is a side elevational view, partially in section, of a fuel injector-igniter in accordance with one embodiment of the present invention;

FIG. 2 is a fragmentary cross-sectional view of the discharge end of the fuel injector-igniter of FIG. 1, enlarged for clarity;

FIG. 3 is a fragmentary cross-sectional view of the plunger of FIG. 1, enlarged for clarity; and

FIG. 4 is a fragmentary bottom view of the fuel prechamber retainer.

Referring to the drawings, an injector in accordance with an exemplary embodiment of the present invention is shown in operative association with a cylinder head 12 of a conventional internal combustion engine (not shown). The injector 10 comprises a tubular housing or cylinder 14 having an internal threaded portion 16 at a lower end 18 thereof. An inner surface 19 of the cylinder 14 is honed and polished for a reason to be discussed. A nozzle 20 is threadably engaged with the threaded portion 16' of the cylinder 14 and has a downwardly extending throat portion 22 having a threaded portion 24 thereon to facilitate engagement in an aperture 26, for example a conventional spark plug aperture, in the cylinder head 12.

Referring to FIG. 2, the nozzle 26 has a central, truncated conical, upwardly convergent, discharge passage 28 therein that communicates with a discharge orifice 29.

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The nozzle 20 has an annular upper end face 30 that is disposed in juxtaposed relation against a fuel pre-chamber retainer 32. A sealing washer 33 is disposed in a recess 34 in the end face 30 and functions as a fluid seal between the nozzle 20 and the retainer 32. The retainer 32 is seated against an annular shoulder 35 on the inner surface 19 of the cylinder 14.

The retainer 32 has a downwardly extending tubular nipple portion 36 with a central cavity or fuel pro-chamber 38 therein for a reason to be discussed hereinafter. The fuel pre-chamber 38 is closed at its lower end by an end wall 40 of downwardly convergent conical cross section that, in conjunction with the tubular nipple portion 36 of the retainer 32, defines the fuel pre-chamber 38. As best seen in FIG. 2, the passages 42 in the end Wall 40 terminate at a point below the uppermost point of the passages 44 in the end wall due to the conical crosssection of the end wall 40 and the orientation of the passages 42 and 44 therein.

Because the disclosed embodiment of the fuel injectorigniter of the present invention is designed for use on a relatively small two-stroke cycle engine, the maximum amount of fuel injected during each cycle is less than .001 cubic inch. This relatively small fuel droplet resides in the center of the conical depression defined by the end wall 40 on the chamber 32. It is to be noted that in this position the fuel droplet is within the fuel prechamber 38 yet is not large enough to cover the air holes 44. As soon as the valve 54 opens, compressed air passes downwardly through the holes 44 into the annulus 46. Mixing of fuel and air occurs in the annulus 46 and in the conical passages between the valve 54 and nipple portion 36 of the retainer 32. Thus, the air and fuel are injected through the passages 42 and '44 into the annulus 46, pulverization and ignition of the fuel taking place therein due to the temperature of the air.

The end wall 40 of the fuel pre-chamber 38 has a plurality of passages 42 that extend radially outwardly and downwardly with respect to the longitudinal axis of the fuel pre-chamber 38 for the passage of fluid outwardly thereof. The passages 42 are disposed at an angle with respect to the longitudinal axis of the fuel pre-chamber 38 similar to the angle of the end wall 40. A plurality of passageways 44 extend vertically through the end wall 40 and are arranged in generally diametrically spaced relation. The passageways 44 communicate with the fuel pre-chamber 38 and a discharge annulus 46 on the lower face of the end wall 40. The discharge annulus 46 is defined by an annular horizontal surface 48 in conjunction with a circular side wall 49 on an apex 52 of the conical end wall 40.

A cup valve 54 having a tubular portion 56, a radially outwardly extending flange portion 58 at the upper end of the tubular portion 56, and a truncated conical portion 60 at the lower end thereof, is disposed about the tubular side wall or nipple portion 36 and end wall 40 of the fuel pre-chamber 38 in telescoping or nesting relationship. The conical portion 60 of the cup valve 54 terminates in a tubular lower end portion 62 having a central aperture 64 that communicates with the discharge orifice 29 in the nozzle 20 for the passage of fluid outwardly of the fuel annulus 46 as will be described.

The cup valve 54 is biased upwardly with respect to the nipple portion 36 by an annular spring 66 comprising a plurality of dished Washers known as Belleville washers 68 that are stacked with the axially displaced radially inwardly extending portions 69 thereof in juxtaposed relationship. The spring 66 extends between an annular spring seat 70 inthe nozzle 20 and the radially outwardly directed flange 58 on the cup valve 54. The cup retainer 32 has a chamfered edge portion 74 leading 3 into the fuel pre-chamber 38 thereof for a reason to be discussed.

An upper end portion of the tubular housing 14 has a threaded internal portion 102 for the acceptance of a suitably threaded plunger shaft guide 104. The shaft guide 104 is located axially with respect to the housing 14 as by a shoulder 106 on the inner peripheral surface 19 of the housing 14. The shaft guide 104 has a plurality of apertures 107 extending longitudinally therethrough for venting purposes. The shaft guide 104 has a central bore 108 for the acceptance of a shaft bushing 110 that is retained therein as by a press fit.

A plunger shaft 112 is supported and guided by the bushing 110 for reciprocable movement longitudinally of the housing 14. The shaft 112 has a lower end portion 114 (FIG. 3) having a threaded portion 116 thereon for engagement in a suitably threaded bore 118 in a plunger 120. The plunger 120 is additionally secured to the shaft 112 by a washer 122 and a lock washer 124 that are biased against the plunger 120 as by a nut 126. The nut 126, lock washer 124 and hold-down Washer 122 preclude backing off of the shaft 112 with respect to the plunger 120.

The plunger 12% has an annular flange 128 at the lower end thereof for the support of an annular lower sealing ring 130'. The lower sealing ring 130 is engageable with the inner surface 19 of the tubular housing 14 in slidable fluid sealing relationship. The sealing ring 130 has a radially inwardly and downwardly convergent chain-fer 132 on its inner peripheral face for engagement with a complementary chamfered cam face 133 on an annular collar 134. The collar 134 surrounds the plunger 120 and has an upwardly radially inwardly chamfered cam face 135 complementary to a radially inwardly and upwardly convergent chamfered face 136 on an upper sealing ring 137. Upon advancement of the nut 126, the washer 122 biases the upper sealing ring 137 downwardly against the collar 134. The complementary surfaces 135 and 136 coact to bias the sealing ring 137 into intimate sealing relationship with the inner surface 19 of the housing 14. Similarly, the downward bias on the collar 134 effects a radial outward bias on the lower sealing ring 130 through a coaction between the surfaces 132 and 133 on the sealing ring 130 and collar 134, respectively.

The plunger 120 has a central bore therein (FIG. 3) for the acceptance of a fuel metering diaphragm 152. A tulip spring 154 comprising an annular portion 155 having a plurality of arcuate downwardly depending fingers 156 thereon is disposed about the diaphragm 152 to hold the diaphragm 152 in a radially inwardly contracted position with respect to the counterbore 150 in the plunger 120.

The diaphragm 152 is sealably biased against an annular transverse seat 157 of the bore 150 by end face 158 on a lower end extension 159 of the shaft 112. The lower extension 159 of the shaft 112 has an upwardly convergent conical seat 160 that engages a complementary conical upper end face 161 on a fuel isolation tube 162. The isolation tube 162 has a threaded upper end portion 163 for engagement in a suitably threaded bore 164 in the plunger 120. The bore 164 has a counterbore 166 therein with an end face 167 for the seating of a flange 168 on the fuel isolation tube 162, thereby to position the isolation tube 162 axially with respect to the plunger 120.

The isolation tube 162 has a central passageway 169 that extends longitudinally therethrough and communicates with a constricted discharge orifice 170 in a discharge head portion 171. The discharge head portion 171 has a downwardly convergent conical lower end face 172 complementary to the conical lower end wall 40 of the fuel pre-chamber 38 in the retainer 32. The isolation tube 162 has a plurality of longitudinally extending grooves 173 diametrically spaced around the outer periphery thereof for a reason to be discussed.

The central passageway 169 of the isolation tube 162 terminates, at its upper end, in a chamfered edge face 174 that functions as a seat for a valve or shuttle 176 that is slidable longitudinally of the plunger shaft 112 in a bore or shuttle chamber 178 therein. The bore 178 has a truncated conical upper end seat 180 for the seating of the shuttle 176 at an upper position therein. The shuttle 176 has a pair of truncated conical seating surfaces 181 and 182 complementary to the seats 174 and 180, respectively.

A passageway 183 extends longitudinally of the'plunger shaft 112 and communicates with the shuttle chamber 178 and an upper central bore 184 in the plunger shaft 112 to facilitate passage of fuel axially of the plunger shaft 112 into the shuttle chamber 178. The lower extension 159 of the plunger shaft 112, within the bore 150, has an annular circumferential recess 185 of arcuate vertical cross section that, in conjunction with the diaphragm 152 and a transverse bore 188 in the plunger shaft 112, defines a fuel metering chamber 189. The transverse bore 183 communicates with the longitudinal shuttle chamber 178 in the plunger shaft 112 and with the diaphragm 152.

The diaphragm 152 is sealably seated at its upper end against a diaphragm seat 190 on the plunger shaft 112 upon advancement of the plunger shaft 112 into the threaded bore 118 in the plunger 128. The diaphragm 152 and the annular portion 155 of the spring 154 are clamped between the diaphragm seat 199 and a complementary seat 191 on the plunger 120.

A threaded upper end portion 192 of the shaft 122 is accepted in a suitably threaded bore 193 in a spring retainer 194. The spring retainer 194 is seated against a suitable washer 196 that is located by a shoulder 197 on the upper end 192 of the shaft 112. The spring retainer 194 has a radially outwardly extending peripheral flange 198 thereon that acts as a seat for one end 199 of an operating spring zen. The operating spring 200 extends between the flange 198 and an upper end face 201 on the shaft guide 104 and operates in compression to normally bias the shaft 112 upwardly, as seen in the drawings, with respect to the housing 14 and nozzle 20.

The upper end portion 192 of the shaft 112 has a threaded bore 202 therein for the acceptance of a conventional self contracting fitting 204 for the sealing retention of a conduit 206 in fluid communicating relationship with the bore 184 in the shaft 112. Fuel is conducted into the bore 184 under pressure from a conventional fuel pump (not shown).

In operation, the shaft 112 and plunger 120 of the fuel injector-igniter 10 are biased downwardly with respect to the housing 14 and nozzle 20 at an appropriate time by any suitable means, for example a cam finger 208. The cam finger 208 may be operated by a suitable cam shaft 210 connected to the rotating components of the engine (not shown) in any suitable manner.

The tubular housing 14 has a plurality of circumferentially spaced apertures 218 therein for the induction of fresh air into a compression chamber 220 defined by the plunger 120, fuel pre-chamber retainer 32 and the inner side walls 19 of the cylinder 14. The apertures 218 are opened to the outside atmosphere upon passage of the plunger 12%) upwardly in the tubular housing under the bias of the spring 200.

Upon actuation of the plunger 120 downwardly in the housing 14, the apertures 218 are closed. Air within the chamber 220 is then compressed as the plunger 120 moves downwardly until the pressure thereof acting through the passages 44 and annulu 46 is sufficient to bias the cup valve 54 downwardly against the upward bias of the spring 66. The resilience of the spring 66 is so determined that the air within the chamber 220 must be supercompressed so as to have a temperature sufiicient to insure ignition of the fuel charge when the air is admixed with the fuel, the fuel charge having been disposed in the fuel pre-chamber 38 on a previous cycle of the plunger 120. Thus, air within the chamber 220 is compressed sufficiently to raise its temperature well above the self-ignition temperature of the fuel when atomized and sufficient to open the cup Valve 54, thereby permitting the compressed air and fuel to pass through the apertures 42 and 44 into the annulus 46, and downwardly through the discharge orifice 64. The passage of high pressure air and fuel simultaneously through the discharge orifices 64 and 29 pulverizes the fuel into a finely divided spray, which thereupon ignites and passes downwardly through the discharge passage 28. When the cup valve 54 opens, the ignited fuel charge passes into the combustion chamber of the engine (not shown), supplying energy thereto. It is to be noted that the fuel is atomized and ignited prior to introduction thereof into the combustion chamber, ignition of the atomized spray occurring in the orifices 64 and 29 and continuing into the discharge passage 28.

Substantially, the entire portion of the air compressed within the chamber 220 and the fuel disposed within the fuel pre-chamber 38 is carried outwardly of the fuel prechamber 38 and mixed with fresh air compressed in the working cylinder of the engine (not shown), combustion of the fuel being continuous upon passage into the air mass because of the previous ignition thereof. The ignited fuel continues to be discharged from the fuel pre-chamber 38 until the plunger 12% reaches the end of its stroke, thereby substantially completely clearing all fuel from the fuel pro-chamber 38 in that volume of the air chamber 229 between the plunger 120 and the valve retainer 32 is negligible at the end of the downward stroke of the plunger 120.

Complete exhaustion of the chamber 220 is facilitated by the grooves 173 in the isolation tube 162 which provide for the passage of air downwardly into the fuel prechamber 38. Upon completion of an injection stroke, the cam shaft 210 is rotated, by any suitable means (not shown), to permit upward movement of the shaft 112 and the plunger 120 under the bias of the spring 288. Because the annulus 46 and the passages 42 and 44 are closed due to seating of the cup valve 54 under the bias of the resilient member 66, the first increment of upward movement of the plunger 120 effects a reduction in pressure in the chamber 228. At this time, a metered quantity of fuel is deposited in the fuel pre-chamber 38, preparing the injector for the next compression and ignition stroke.

It is to be noted that once the valve 54 cracks open due to pressure in the annulus 46, a relatively lower pres sure is required to hold the valve 54 open due to the differential effective area thereof between the closed and open positions.

Replenishment of the charge of fuel in the fuel prechamber 38 is accomplished upon the occurrence of the aforementioned pressure reduction in the chamber 220 due to the relief of the radially outward bias on the diaphragm 152 and spring 154.

Upon relief of the radially outward bias thereon, the downwardly depending finger portions 156 of the spring 154 bias the diaphragm 152 radially inwardly against the recess 185 in the plunger shaft 112. This contrac tion of the diaphragm 152 moves a quantity of fuel outwardly of the metering chamber 189 and downwardly through the passage 169 and 170 into the fuel pre-charnber 38. It is to be noted that the foregoing transfer of fuel from the metering chamber 189 into the fuel prechamber 38 during the first increment of upward movement of the plunger 120 is due to the pressure reduction in the chamber 220.

The aforementioned passage of fuel is possible because, at this point, the pressure in both the metering chamber 189 and compression chamber 220 is greater than the fuel pressure in the fuel inlet conduit 206 operative on the upper end of the shuttle 176 and therefore the shuttle 176 is maintained in its uppermost position, permitting the fuel to flow. However, at such time as the pressure of the fuel in the conduit 206 exceeds the pressure in the compression chamber 220, which condition obtains upon further upward movement of the plunger 120, the shuttle 176 is biased downwardly against the seat 174 in the isolation tube 162, thereby terminating the passage of fuel outwardly of the metering chamber 189 and permitting the refilling thereof. The volume of the fuel metering chamber 189 is variable due to expansion of the diaphragm 152 in response to the pressure of the fuel. Increases in fuel pressure expand the diaphragm 152 and the fingers 156 of the spring 154 radially outwardly, thereby enlarging the metering chamber 189 so as to accommodate more fuel therein.

When pressure in the chamber 220, effective on the shuttle 17 6, exceeds the effective pressure of the fuel due to a compression stroke of the plunger 1120, the shuttle 176 is 'biased upwardly against the seat 1 of the shuttle chamber 178. Upward movement of the shuttle 176 closes the passageway 183 against the passage of fuel into the fuel metering chamber 189 and opens the chamber 189 to the pressure within the chamber 220. The increasing pressure within the compression chamber 220 biases the diaphragm 152 and fingers 156 of the spring 154 radially outwardly against the bore 150. The fingers 156 and diaphragm 152 are then conditioned to bias the fuel contained within the metering chamber 189 outwardly thereof upon the establishment of the aforementioned pressure reduction upon the first increment of upward movement of the plunger 120.

From the foregoing description of operation it should be apparent that control of the quantity of fuel injected into the internal combustion engine (not shown) is dependent primarily upon upstreamfuel pressure in the fuel conduit 206. Therefore, the energy input and work output of the engine (not shown) is controlled simply by controlling fuel pressure in the conduit 206.

While it will be apparent that the embodiments of the invention herein disclosed are Well calculated to fulfill the objects of the invention, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

1. A fuel injector-igniter for an internal combustion engine having an expansion chamber, said injector-igniter comprising means for isolating a fuel charge from the expansion chamber comprising a fuel pre-chamber, means for compressing a fluid in isolated relationship with respect to the expansion chamber to a predetermined pressure and temperature suflicient to ignite said fuel, means for admixing fluid with said fuel to ignite said fuel comprising a fuel and fluid annulus underlying said fuel prechamber, a plurality of passage means communicating with said fuel pro-chamber and said annulus and a valve means normally closing said annulus with respect to the expansion chamber, and means for injecting said ignited fuel into said expansion chamber comprising an orifice in said valve means communicating with said annulus and the expansion chamber upon the occurrence of a predetermined pressure of said fluid.

2. A fuel injector-igniter in accordance with claim 1 wherein said valve is maintainable in the open condition by a relatively smaller pressure than said predetermined pressure.

3. A fuel injector-igniter for an internal combustion engine having an expansion chamber, said injector-igniter comprising a cup-shaped fuel pre-chamber for isolating a fuel charge from the expansion chamber, a cup-shaped valve underlying said fuel pre-chamber in nesting relationship, passage means communicating with said fuel prechamber normally closed by said valve, means for compressing a fluid in isolated relationship with respect to the expansion chamber to a predetermined pressure and temperature sufiicient to ignite said fuel, resilient means normally biasing said valve to the closed position, means for admixing said fluid with said fuel to ignite said fuel upon the occurrence of said predeterminable pressure comprising a passage openable upon movement of said valve extending between said first-mentioned passage means and an orifice in said valve whereby said ignited fuel is injected into the expansion chamber.

4, A fuel injector-igniter for an internal combustion engine having an expansion chamber, said injector-igniter comprising a cylinder having an aperture in the side wall thereof, a plunger reciprocable Within said cylinder to close said aperture with respect to one end thereof and to compress a fluid therein to a predetermined pressure, an end wall at said one end of said cylinder having a fuel pre-chamber therein for isolating a fuel charge from the expansion chamber, tubular means on said plunger acceptable within said fuel pro-chamber for depositing a charge of fuel therein, fuel metering means in said plunger comprising a recess having a resilient diaphragm therein, spring means normally collapsing said diaphragm to a relatively small volume, a fuel inlet aperture in said recess for communication with a source of fuel under pressure relatively lower than said predetermined pressure, a fuel outlet in said recess cornmunicating with said tubular means, a shuttle valve for closing said fuel inlet upon the occurrence of said predetermined pressure of said fluid whereupon said fluid expands said diaphragm to a relatively large volume, said spring means being operable to bias said diaphragm to a relatively smaller volume upon a reduction in said predetermined pressure thereby to pump fuel outwardly of said diaphragm, said shuttle valve closing said fuel outlet upon a further reduction of said fluid pressure whereby said fuel expands said diaphragm to a volume larger than said relative small volume, and valve means openable upon the occurrence of said predetermined fluid pressure to admix said fluid with the fuel in said fuel pre-chamber thereby to ignite said fuel.

5. A fuel injector-igniter for an internal combustion engine having an expansion chamber, said injector-igniter comprising means for isolating a fuel charge from the expansion chamber, means for compressing a fluid in isolated relationship with respect to the expansion chamber to a predetermined pressure and temperature sufficient to ignite said fuel, and means for admixing the fluid with said fuel to ignite said fuel upon the occurrence of said predetermined pressure comprising a cup-shaped valve normally closing said isolating means with respect to the expansion chamber, a plurality of dished washers stacked with the radially inwardly axially displaced portions thereof in juxtaposed relationship to form a resilient means for biasing said valve to the closed position and an orifice in said valve normally closed by said isolating means.

References Cited in the file of this patent UNITED STATES PATENTS 2,091,987 Honn Sept. 7, 1937 2,203,669 Butler June 11, 1940 2,642,315 French June 16, 1953 FOREIGN PATENTS 7,563 Great Britain Jan. 6, 1910 469,107 France May 11, 1914 

